Umthelela we-Pseudomonas aeruginosa Marine Biofilm ku-Microbial Corrosion ye-2707 Super Duplex Stainless Steel

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I-Microbial corrosion (MIC) iyinkinga enkulu ezimbonini eziningi ngoba ingaholela ekulahlekelweni okukhulu kwezomnotho.I-Super duplex stainless steel 2707 (2707 HDSS) isetshenziswa ezindaweni zasolwandle ngenxa yokumelana kwayo okuhle kakhulu namakhemikhali.Kodwa-ke, ukumelana kwayo ne-MIC akukaze kuboniswe ngokuhlolwa.Lolu cwaningo luhlole ukuziphatha kwe-MIC 2707 HDSS okubangelwa i-marine aerobic bacterium i-Pseudomonas aeruginosa.Ukuhlaziywa kwe-electrochemical kubonise ukuthi phambi kwe-Pseudomonas aeruginosa biofilm ku-2216E medium, amandla okugqwala ashintsha kahle, futhi ukugqwala kwamanje kwanda.Imiphumela yokuhlaziywa kwe-X-ray photoelectron spectroscopy (XPS) ibonise ukwehla kokuqukethwe kwe-Cr endaweni eyisampula ngaphansi kwe-biofilm.Ukuhlaziywa kwezithombe zomgodi kubonise ukuthi i-Pseudomonas aeruginosa biofilms ikhiqize ukujula komgodi okukhulu okungu-0.69 µm ngemva kwezinsuku eziyi-14 zesiko.Nakuba lokhu kukuncane, kuphakamisa ukuthi i-2707 HDSS ayivikelekile ngokuphelele emiphumeleni ye-P. aeruginosa biofilms ku-MIC.
Insimbi engagqwali ye-Duplex (DSS) isetshenziswa kabanzi ezimbonini ezahlukahlukene ngenxa yenhlanganisela ephelele yezakhiwo ezinhle kakhulu zemishini kanye nokumelana nokugqwala1,2.Kodwa-ke, i-pitting yendawo ingase ivele, okungase kuthinte ubuqotho bale nsimbi 3, 4.I-DSS ayivikelekile ekugqwaleni kwe-microbial (MIC)5,6.Nakuba uhla lokusetshenziswa kwe-DSS lubanzi kakhulu, zisekhona izindawo lapho ukumelana nokugqwala kwe-DSS kunganele ukusetshenziswa kwesikhathi eside.Lokhu kusho ukuthi izinto ezibiza kakhulu ezinokumelana nokugqwala okuphezulu ziyadingeka.U-Jeon et al.7 bathole ukuthi ngisho ne-super duplex stainless steel (SDSS) inemikhawulo ethile mayelana nokumelana nokugqwala.Ngakho-ke, kunesidingo se-super duplex stainless steels (HDSS) enokumelana nokugqwala okuphezulu kwezinye izinhlelo zokusebenza.Lokhu kuholele ekuthuthukisweni kwe-HDSS ene-alloyed kakhulu.
Ukumelana nokugqwala kwe-DSS kunqunywa isilinganiso se-α-isigaba ku-γ-isigaba kanye nezindawo eziqedwe ku-Cr, Mo no-W eduze kwezigaba zesibili8,9,10.I-HDSS iqukethe okuqukethwe okuphezulu kwe-Cr, Mo ne-N11, okukunikeza ukumelana nokugqwala okuhle kakhulu kanye nenani eliphezulu (45-50) elilingana nenani lokumelana ne-pitting (PREN), elichazwa yi-wt.% Cr + 3.3 (wt.% Mo + 0, 5 wt % W) + 16 wt %.N12.Ukumelana nokugqwala kwayo okuhle kakhulu kuncike ekwakhiweni okunokulinganisela okuqukethe cishe izigaba ze-ferritic (α) nezingu-50% ze-austenitic (γ).I-HDSS ithuthukise izakhiwo zemishini kanye nokumelana okuphezulu kwe-chlorine uma kuqhathaniswa ne-DSS13 evamile.Izici zokugqwala kwamakhemikhali.Ukumelana nokugqwala okuthuthukisiwe kunweba ukusetshenziswa kwe-HDSS ezindaweni ezine-chloride ezinolaka njengezindawo zasolwandle.
I-MIC iyinkinga enkulu ezimbonini eziningi, ezihlanganisa uwoyela negesi kanye nokuhlinzekwa kwamanzi14.I-MIC yenza u-20% wawo wonke umonakalo wokugqwala15.I-MIC i-bioelectrochemical corrosion engabonwa ezindaweni eziningi16.Ukwakheka kwama-biofilms ezindaweni zensimbi kushintsha izimo ze-electrochemical futhi ngaleyo ndlela kube nomthelela enqubweni yokugqwala.Kuyamukelwa ngokuvamile ukuthi ukugqwala kwe-MIC kubangelwa i-biofilms14.Ama-microorganisms e-Electrogenic adla izinsimbi ukuze athole amandla okuphila17.Ucwaningo lwakamuva lwe-MIC lubonise ukuthi i-EET (i-extracellular electron transfer) iyisici esikhawulelayo se-MIC esibangelwa ama-electrogenic microorganisms.U-Zhang et al.18 babonise ukuthi abaxhumanisi bama-electron basheshisa ukudluliswa kwama-electron phakathi kwamaseli e-Desulfovibrio vulgaris sessile kanye nensimbi engagqwali engu-304, okuholela ekuhlaselweni okuqine kakhulu kwe-MIC.U-Anning et al.19 kanye noWenzlaff et al.20 ibonise ukuthi ama-biofilms we-corrosive sulfate-reducing bacteria (SRBs) angakwazi ukumunca ama-electron ngokuqondile kuma-substrates ensimbi, okuholela ekugobeni okukhulu.
I-DSS yaziwa ukuthi ingenwa kalula yi-MIC kumidiya equkethe ama-SRB, amagciwane e-iron-reducing (IRBs), njll. 21 .Lawa mabhaktheriya abangela umgodi wendawo endaweni ye-DSS ngaphansi kwe-biofilm22,23.Ngokungafani ne-DSS, kuncane okwaziwayo nge-MIC HDSS24.
I-Pseudomonas aeruginosa iyi-bacterium e-Gram-negative, e-motile, emise okwenduku esatshalaliswa kabanzi emvelweni25.I-Pseudomonas aeruginosa futhi iyi-microbiota eyinhloko ebhekele i-MIC yensimbi endaweni yasolwandle26.Izinhlobo ze-Pseudomonas zihileleke ngokuqondile ezinqubweni zokugqwala futhi ziqashelwa njengamakoloni okuqala ngesikhathi sokwakheka kwe-biofilm27.UMahat et al.28 kanye noYuan et al.29 ibonise ukuthi i-Pseudomonas aeruginosa ithambekele ekukhuphuleni izinga lokugqwala kwensimbi emnene nama-alloys ezindaweni zasemanzini.
Umgomo oyinhloko walo msebenzi ukutadisha izakhiwo ze-MIC ze-2707 HDSS ezibangelwa i-marine aerobic bacterium i-Pseudomonas aeruginosa kusetshenziswa izindlela ze-electrochemical, izindlela zokuhlaziya indawo kanye nokuhlaziywa komkhiqizo wokugqwala.Izifundo ze-Electrochemical ezihlanganisa amandla wesekethe evulekile (OCP), ukumelana ne-linear polarization (LPR), i-electrochemical impedance spectroscopy (EIS) kanye ne-dynamic polarization eyenziwa ukuze kufundwe ukuziphatha kwe-MIC 2707 HDSS.Ukuhlaziywa kwe-energy dispersive spectroscopy (EDS) kwenziwa ukuze kutholwe izakhi zamakhemikhali ezindaweni ezigqwalile.Ngaphezu kwalokho, ukuzinza kwefilimu ye-oxide passivation ngaphansi kwethonya lemvelo yasolwandle equkethe i-Pseudomonas aeruginosa kunqunywe yi-X-ray photoelectron spectroscopy (XPS).Ukujula kwemigodi kukalwe ngaphansi kwe-confocal laser scanning microscope (CLSM).
Ithebula 1 libonisa ukwakheka kwamakhemikhali okungu-2707 HDSS.Ithebula 2 libonisa ukuthi i-2707 HDSS inezakhiwo ezinhle kakhulu zemishini ezinamandla okukhiqiza angu-650 MPa.Emkhiwaneni.1 ikhombisa i-optical microstructure yokushisa kwesixazululo okuphathwe okungu-2707 HDSS.Amabhendi amade ezigaba ze-austenitic ne-ferritic ngaphandle kwezigaba zesibili angabonakala kusakhiwo se-microstructure esiqukethe cishe izigaba ze-austenitic ezingu-50% nezingu-50%.
Emkhiwaneni.I-2a ibonisa amandla esekethe evulekile (Eocp) ngokumelene nesikhathi sokuchayeka se-2707 HDSS ku-2216E abiotic medium kanye nomhluzi we-Pseudomonas aeruginosa izinsuku ezingu-14 ku-37°C.Kutholwe ukuthi izinguquko eziphawuleka kakhulu ku-Eocp zenzeka emahoreni okuqala angama-24.Amanani e-EoCP kuzo zombili izimo afinyelele inani eliphakeme cishe ku- -145 mV (ngokuqhathaniswa ne-SCE) cishe amahora angu-16 abese ehla ngokucijile afinyelela ku- -477 mV (ngokuqhathaniswa ne-SCE) kanye -236 mV (ngokuqhathaniswa ne-SCE) kumasampuli angewona awebhayoloji kanye no-P ngesihlobo. SCE) amaqabunga e-patina, ngokulandelana.Ngemva kwamahora angu-24, inani le-Eocp le-Pseudomonas aeruginosa 2707 HDSS lahlala lizinzile ku- -228 mV (uma kuqhathaniswa ne-SCE), kuyilapho inani elihambisanayo lesampula okungeyona eyebhayoloji lalicishe libe ngu--442 mV (uma kuqhathaniswa ne-SCE).I-Eocp ebukhoneni be-Pseudomonas aeruginosa yayiphansi kakhulu.
Ukuhlolwa kwe-electrochemical kwamasampuli angu-2707 HDSS kumidiya ye-abiotic kanye nomhluzi we-Pseudomonas aeruginosa ku-37°C:
(a) Ushintsho ku-Eocp ngesikhathi sokuchayeka, (b) ijika le-polarization ngosuku olungu-14, (c) ushintsho ku-Rp nesikhathi sokuchayeka, (d) ukuguquka kokuhambisana nesikhathi sokuchayeka.
Ithebula lesi-3 libonisa imingcele yokugqwala kwe-electrochemical yamasampula e-HDSS angu-2707 avezwe kumidiya egonyelwe i-abiotic kanye ne-P. aeruginosa esikhathini esiyizinsuku eziyi-14.I-Tangential extrapolation ye-anodic ne-cathodic curves endaweni yokuhlangana ivumele ukunqunywa kwe-corrosion current density (icorr), amandla okugqwala (Ecorr) kanye ne-Tafel slope (βα ne-βc) ngokwezindlela ezijwayelekile30,31.
Njengoba kuboniswe kuMfanekiso 2b, ukushintshwa okuphezulu kwejika le-P. aeruginosa kubangele ukwanda kwe-Ecorr uma kuqhathaniswa nejika le-abiotic.Inani le-icorr lesampula eliqukethe i-Pseudomonas aeruginosa, ngokulingana nezinga lokugqwala, likhuphuke laya ku-0.328 µA cm-2, elikhulu ngokuphindwe kane kunesampula okungezona ezebhayoloji (0.087 µA cm-2).
I-LPR iyindlela yakudala ye-electrochemical yokuhlaziya okungabhubhisi kokugqwala.Iphinde yasetshenziswa ukutadisha i-MIC32.Emkhiwaneni.I-2c ibonisa ushintsho ekumelaneni ne-polarization (Rp) kuye ngesikhathi sokuchayeka.Inani eliphakeme le-Rp lisho ukugqwala okuncane.Phakathi namahora angu-24 okuqala, i-Rp 2707 HDSS ifinyelele u-1955 kΩ cm2 kumasampula okungezona ezebhayoloji kanye no-1429 kΩ cm2 kumasampula e-Pseudomonas aeruginosa.Umfanekiso 2c futhi ubonisa ukuthi inani le-Rp lehle ngokushesha ngemva kosuku olulodwa futhi lahlala lingashintshile uma kuqhathaniswa ezinsukwini eziyi-13 ezilandelayo.Inani le-Rp lesampula lokuhlola i-Pseudomonas aeruginosa licishe libe ngu-40 kΩ cm2, eliphansi kakhulu kunevelu engu-450 kΩ cm2 yesifanekiso sokuhlola okungezona ezebhayoloji.
Inani le-icorr lilingana nezinga lokugqwala elifanayo.Inani layo lingabalwa kusukela kuzibalo ezilandelayo ze-Stern-Giri:
Ngokusho kukaZoe et al.33 umthamo we-Tafel B uthathwe njengenani elijwayelekile elingu-26 mV/dec kulo msebenzi.Emkhiwaneni.I-2d ibonisa ukuthi i-icorr yohlobo lwe-abiotic lwe-2707 yahlala izinzile, kuyilapho i-icorr yebhendi ye-Pseudomonas aeruginosa ishintshashintsha kakhulu ngokugxuma okukhulu ngemva kwamahora angu-24 okuqala.Inani le-icorr lesampula lokuhlola le-Pseudomonas aeruginosa laliwuhlelo lobukhulu obuphezulu kunalelo lokulawula okungekona okwebhayoloji.Lo mkhuba uhambisana nemiphumela yokumelana ne-polarization.
I-EIS ingenye indlela engacekeli phansi esetshenziswa ukukhombisa ukusabela kwe-electrochemical endaweni yokugqwala34.Izibalo ze-Impedance spectra kanye ne-capacitance yemigqa evezwe kumidiya ye-abiotic nezixazululo ze-Pseudomonas aeruginosa, i-Rb ukumelana kwe-passive/biofilm okwakhiwa phezu komugqa, i-Rct ukumelana nokushajwa kokushaja, i-Cdl iyingqimba ephindwe kabili kagesi.) kanye nemingcele ye-QCPE yesigaba esiqhubekayo (CPE).Le mingcele yabuye yahlaziywa ngokuqhathanisa idatha nemodeli yesekethe kagesi elinganayo (EEC).
Emkhiwaneni.3 ibonisa iziza zeNyquist ezijwayelekile (a no-b) kanye neziza ze-Bode (a' kanye no-b') zamasampuli angu-2707 HDSS kumidiya ye-abiotic kanye nomhluzi we-Pseudomonas aeruginosa ngezikhathi ezihlukahlukene zokufukamela.Ebukhoneni be-Pseudomonas aeruginosa, ububanzi beluphu yeNyquist buyancipha.Isakhiwo se-Bode (Fig. 3b') sibonisa ukwanda kwe-impedance ephelele.Ulwazi mayelana nesikhathi sokuphumula esingaguquki lungatholakala ku-phase maxima.Emkhiwaneni.4 ikhombisa izakhiwo ezibonakalayo kanye ne-EEC ehambisanayo esekelwe kusendlalelo esisodwa (a) nesendlalelo ezimbili (b).I-CPE yethulwa kumodeli we-EEC.Ukwemukelwa kwayo kanye nokuvinjwa kwayo kuvezwa kanje:
Amamodeli amabili angokomzimba namasekhethi afanayo afanayo wokufaka i-2707 HDSS coupon impedance spectrum:
Lapho u-Y0 engubukhulu be-CPE, j inombolo ecatshangwayo noma (−1)1/2, ω imvamisa ye-angular, futhi n iyisici samandla e-CPE esingaphansi kwe-135.Ukuguqulwa kokumelana nokudluliswa kweshaji (okungukuthi 1/Rct) kuhambisana nezinga lokugqwala.Inani eliphansi le-Rct lisho izinga eliphezulu lokugqwala27.Ngemuva kwezinsuku eziyi-14 zokufukamela, i-Rct yesampula yokuhlola ye-Pseudomonas aeruginosa ifinyelele ku-32 kΩ cm2, okungaphansi kakhulu kuka-489 kΩ cm2 wesampula yokuhlola okungezona ezebhayoloji (Ithebula 4).
Izithombe ze-CLSM nemifanekiso ye-SEM kufig.5 ikhombisa ngokusobala ukuthi ukumbozwa kwe-biofilm ebusweni besampula ye-HDSS 2707 bekuminyene kakhulu ngemuva kwezinsuku eziyi-7.Kodwa-ke, ngemuva kwezinsuku eziyi-14 ukumbozwa kwe-biofilm kwaba yingcosana futhi kwavela amaseli afile.Ithebula lesi-5 libonisa ukushuba kwe-biofilm kwamasampuli angu-2707 HDSS ngemva kwezinsuku eziyi-7 neziyi-14 zokuchayeka ku-Pseudomonas aeruginosa.Ubukhulu obukhulu befilimu ye-biofilm bushintshile ukusuka ku-23.4 µm ngemva kwezinsuku ezingu-7 ukuya ku-18.9 µm ngemva kwezinsuku ezingu-14.Isilinganiso esimaphakathi se-biofilm siphinde saqinisekisa lo mkhuba.Yehla isuka ku-22.2 ± 0.7 μm ngemva kwezinsuku ezingu-7 yaya ku-17.8 ± 1.0 μm ngemva kwezinsuku eziyi-14.
(a) Isithombe se-3-D CLSM ngezinsuku ezingu-7, (b) isithombe se-3-D CLSM ezinsukwini eziyi-14, (c) Isithombe se-SEM ezinsukwini ezingu-7, kanye (d) nesithombe se-SEM ezinsukwini eziyi-14.
I-EMF yembule izakhi zamakhemikhali ku-biofilm kanye nemikhiqizo yokugqwala kumasampuli avezwe ku-Pseudomonas aeruginosa izinsuku eziyi-14.Emkhiwaneni.Umfanekiso wesi-6 ubonisa ukuthi okuqukethwe kwe-C, N, O, P ku-biofilm kanye nemikhiqizo yokugqwala kuphakeme kakhulu kunensimbi ehlanzekile, njengoba lezi zakhi zihlotshaniswa ne-biofilm kanye nama-metabolites ayo.Ama-microorganisms adinga kuphela amanani okulandelela we-Cr ne-Fe.Okuqukethwe okuphezulu kwe-Cr no-Fe ku-biofilm kanye nemikhiqizo yokugqwala ebusweni besampula kubonisa ukulahleka kwezakhi ku-matrix yensimbi ngenxa yokugqwala.
Ngemuva kwezinsuku eziyi-14, imigodi ene-P. aeruginosa nangaphandle kwayo yabonwa ku-2216E ephakathi.Ngaphambi ekufukameleni, ebusweni amasampula kwaba bushelelezi futhi ngaphandle amaphutha (Fig. 7a).Ngemva kokufakwa kanye nokukhishwa kwemikhiqizo ye-biofilm kanye ne-corrosion, imigodi ejulile ebusweni besampula yahlolwa kusetshenziswa i-CLSM, njengoba kuboniswe ku-Fig. 7b no-c.Akukho mgodi osobala otholakele endaweni yokulawula okungeyona eyebhayoloji (ubukhulu bomgodi wokujula ngu-0.02 µm).Ubukhulu bokujula komgodi okudalwe i-Pseudomonas aeruginosa kwaba ngu-0.52 µm ngemva kwezinsuku ezingu-7 kanye no-0.69 µm ngemva kwezinsuku ezingu-14, ngokusekelwe ekujuleni komgodi okumaphakathi okumaphakathi kusuka kumasampuli angu-3 (ubukhulu bomgodi wokujula obungu-10 bukhethiwe kusampula ngayinye) futhi kwafinyelela ku-0. 42 ± 0.12 µm .kanye no-0.52 ± 0.15 µm, ngokulandelanayo (Ithebula 5).Lawa manani okujula kwe-dimple mancane kodwa abalulekile.
(a) ngaphambi kokuchayeka;(b) izinsuku eziyi-14 endaweni yemvelo;(c) izinsuku eziyi-14 kumhluzi we-P. aeruginosa.
Emkhiwaneni.Ithebula lesi-8 libonisa i-spectra ye-XPS yezindawo ezihlukene zesampula, futhi ikhemistri ehlaziywe indawo ngayinye ifinyezwa kuThebula 6. Kuthebula lesi-6, amaphesenti e-athomu e-Fe ne-Cr abephansi kakhulu ebukhoneni be-P. aeruginosa (amasampuli A no-B ) kunasemigqeni yokulawula okungeyona eyebhayoloji.(amasampula C no-D).Kusampula ye-Pseudomonas aeruginosa, ijika le-spectral eliyinhloko le-Cr 2p lifakwe ezingxenyeni ezine eziphezulu ezinamandla abophezelayo (BE) angu-574.4, 576.6, 578.3 kanye no-586.8 eV, anikezwe i-Cr, Cr2O3, CR(O3, Cr(O3) kanye ne-CR(O3) 3, ngokulandelana (Fig. 9a kanye b).Kumasampuli angewona awebhayoloji, i-spectra yeleveli eyinhloko i-Cr 2p ku-Figs.I-9c kanye ne-d iqukethe iziqongo ezimbili eziyinhloko ze-Cr (BE 573.80 eV) ne-Cr2O3 (BE 575.90 eV), ngokulandelanayo.Umehluko omangalisa kakhulu phakathi kwekhuphoni le-abiotic kanye nekhuphoni ye-P. aeruginosa ubukhona be-Cr6+ kanye nengxenye ephezulu kakhulu ye-Cr(OH)3 (BE 586.8 eV) ngaphansi kwe-biofilm.
I-spectra ebanzi ye-XPS yamasampuli angu-2707 HDSS kumidiya emibili izinsuku ezingu-7 neziyi-14, ngokulandelana.
(a) Izinsuku eziyi-7 zokuchayeka ku-P. aeruginosa, (b) izinsuku eziyi-14 zokuchayeka ku-P. aeruginosa, (c) izinsuku eziyi-7 zokuchayeka ku-abiotic, (d) izinsuku eziyi-14 zokuchayeka ku-abiotic.
I-HDSS ibonisa izinga eliphezulu lokumelana nokugqwala ezindaweni eziningi.UKim et al.2 ubike ukuthi i-HDSS UNS S32707 ikhonjwe njenge-DSS ene-doped kakhulu ene-PREN enkulu kunokungu-45. Inani le-PREN lesampula le-HDSS 2707 kulo msebenzi lalingu-49. Lokhu kungenxa yokuqukethwe okuphezulu kwe-Cr namazinga aphezulu e-Mo and I-Ni, ewusizo ezindaweni ezine-acidic kanye nezindawo ezinokuqukethwe okuphezulu kwama-chloride.Ngaphezu kwalokho, ukwakheka okulingana kahle kanye ne-microstructure engenasici inikeza ukuzinza kwesakhiwo kanye nokumelana nokugqwala.Naphezu kokumelana okuhle kakhulu kwamakhemikhali, idatha yokuhlola kulo msebenzi ibonisa ukuthi i-2707 HDSS ayigomekile ngokuphelele kuma-MIC e-Pseudomonas aeruginosa biofilm.
Imiphumela ye-Electrochemical ibonise ukuthi izinga lokugqwala le-2707 HDSS ku-Pseudomonas aeruginosa umhluzi landa kakhulu ngemva kwezinsuku ezingu-14 uma kuqhathaniswa nemvelo engeyona yezinto eziphilayo.Emfanekisweni 2a, ukwehla kwe-Eocp kubonwe kokubili ku-abiotic medium naku-P. aeruginosa umhluzi phakathi namahora angu-24 okuqala.Ngemva kwalokho, i-biofilm iqeda ukumboza ubuso besampula bese i-Eocp izinze ngokuqhathaniswa.Nokho, izinga le-biotic Eocp laliphezulu kakhulu kuneleveli ye-Eocp ye-abiotic.Kunezizathu zokukholelwa ukuthi lo mehluko uhlotshaniswa nokwakhiwa kwe-P. aeruginosa biofilms.Emkhiwaneni.2g, inani le-icorr le-2707 HDSS lifinyelele ku-0.627 µA cm-2 phambi kwe-Pseudomonas aeruginosa, okuwuhlelo lobukhulu obungaphezulu kwalelo lokulawulwa okungekona okwebhayoloji (0.063 µA cm-2), okuhambisana ne-Rct inani likalwe nge-EIS.Ezinsukwini ezimbalwa zokuqala, amanani e-impedance kumhluzi we-P. aeruginosa anda ngenxa yokunamathiselwa kwamaseli e-P. aeruginosa kanye nokwakheka kwe-biofilm.Kodwa-ke, i-impedance iyancipha lapho i-biofilm ivala ngokuphelele indawo yesampula.Isendlalelo sokuzivikela sihlaselwa ngokuyinhloko ngenxa yokwakheka kwe-biofilm kanye ne-biofilm metabolites.Ngakho-ke, ukumelana nokugqwala kuncipha ngokuhamba kwesikhathi, futhi idiphozithi ye-Pseudomonas aeruginosa ibangela ukugqwala kwendawo.Amathrendi endaweni ye-abiotic ahlukile.Ukumelana nokugqwala kokulawulwa okungekona okwebhayoloji bekuphakeme kakhulu kunevelu ehambisanayo yamasampuli adalulwe kumhluzi we-Pseudomonas aeruginosa.Ngaphezu kwalokho, kumasampula e-abiotic, inani le-Rct 2707 HDSS lifinyelele ku-489 kΩ cm2 ngosuku lwe-14, eliphindwe izikhathi ezingu-15 kunalapho kukhona i-Pseudomonas aeruginosa (32 kΩ cm2).Ngakho, i-2707 HDSS inokumelana nokugqwala okuhle kakhulu endaweni eyinyumba, kodwa ayivikelekile ekuhlaselweni kwe-MIC yi-Pseudomonas aeruginosa biofilm.
Le miphumela ingabuye ibonwe kusukela kumajika e-polarization ku-Fig.2b.I-anodic branching ihlotshaniswa ne-Pseudomonas aeruginosa biofilm formation kanye nokusabela kwe-oxidation yensimbi.Ngesikhathi esifanayo, ukusabela kwe-cathodic ukuncishiswa kwe-oxygen.Ukuba khona kwe-P. aeruginosa kwandise ngokuphawulekayo ukuminyana kwamanje kokugqwala, okwakumayelana nokuhleleka kobukhulu obuphezulu kunokulawulwa kwe-abiotic.Lokhu kubonise ukuthi i-Pseudomonas aeruginosa biofilm ithuthukise ukugqwala kwendawo kwe-2707 HDSS.U-Yuan et al.29 bathole ukuthi ukugqwala kwamanje kwe-70/30 Cu-Ni alloy kukhuliswe yi-Pseudomonas aeruginosa biofilm.Lokhu kungase kube ngenxa ye-biocatalysis yokunciphisa umoya-mpilo yi-Pseudomonas aeruginosa biofilm.Lokhu kubuka kungase futhi kuchaze i-MIC 2707 HDSS kulo msebenzi.Amafilimu e-Aerobic biofilm nawo anganciphisa okuqukethwe komoyampilo ngaphansi kwawo.Ngakho-ke, ukwenqaba ukubuyisela indawo yensimbi nge-oxygen kungase kube isici esinomthelela ku-MIC kulo msebenzi.
Dickinson et al.38 iphakamise ukuthi izinga lokusabela kwamakhemikhali kanye ne-electrochemical lincike ngokuqondile emsebenzini we-metabolic webhaktheriya elinamathiselwe endaweni eyisampula kanye nemvelo yemikhiqizo yokugqwala.Njengoba kuboniswe kuMfanekiso 5 kanye neThebula 5, inani lamaseli nokuqina kwe-biofilm kwehle ngemva kwezinsuku eziyi-14.Lokhu kungachazwa ngokunengqondo ukuthi ngemva kwezinsuku eziyi-14 iningi lamaseli agxilile endaweni engu-2707 HDSS afa ngenxa yokuncipha kwezakhi endaweni engu-2216E noma ukukhululwa kwama-ion ensimbi anobuthi ku-2707 HDSS matrix.Lona umkhawulo wokuhlolwa kwenqwaba.
Kulo msebenzi, i-Pseudomonas aeruginosa biofilm ikhuthaze ukuchithwa kwendawo kwe-Cr ne-Fe ngaphansi kwe-biofilm ebusweni be-2707 HDSS (Fig. 6).Kuthebula 6, u-Fe no-Cr behle kusampula D uma kuqhathaniswa nesampula C, okubonisa ukuthi ukuqedwa kwe-Fe ne-Cr okubangelwa i-P. aeruginosa biofilm kwanakekelwa ngemva kwezinsuku eziyi-7 zokuqala.Imvelo ye-2216E isetshenziselwa ukulingisa imvelo yasolwandle.Iqukethe i-17700 ppm Cl-, eqhathaniswa nokuqukethwe kwayo emanzini emvelo olwandle.Ukuba khona kwe-17700 ppm Cl- kwakuyisizathu esiyinhloko sokuncipha kwe-Cr kumasampuli ezinsuku ezingu-7 kanye nezinsuku eziyi-14 angewona awebhayoloji ahlaziywa yi-XPS.Uma kuqhathaniswa nesampula yokuhlola ye-Pseudomonas aeruginosa, ukuhlakazwa kwe-Cr kusampula yokuhlola ye-abiotic kuncane kakhulu ngenxa yokumelana okuqinile kwe-2707 HDSS ne-chlorine endaweni ephilayo.Emkhiwaneni.9 ikhombisa ubukhona be-Cr6+ kwifilimu engenzi lutho.Lokhu kungase kuhlobane nokukhishwa kwe-Cr endaweni yensimbi yi-P. aeruginosa biofilms, njengoba kuphakanyiswe u-Chen no-Clayton39.
Ngenxa yokukhula kwebhaktheriya, amanani we-pH ophakathi ngaphambi nangemuva kokufukamela ayengu-7.4 no-8.2, ngokulandelana.Ngakho-ke, ukugqwala kwama-asidi aphilayo mancane amathuba okuba kube neqhaza kulo msebenzi ngaphansi kwe-P. aeruginosa biofilms ngenxa ye-pH ephezulu ngokuqhathaniswa endaweni eyinqwaba.I-pH yendawo yokulawula okungeyona eyebhayoloji ayizange ishintshe kakhulu (kusuka ku-7.4 yokuqala ukuya ku-7.5 yokugcina) phakathi nenkathi yokuhlolwa kwezinsuku eziyi-14.Ukwanda kwe-pH ku-inoculum medium ngemva kokufukamela kwakuhlotshaniswa nomsebenzi we-metabolic we-Pseudomonas aeruginosa, futhi umphumela ofanayo ku-pH watholakala lapho ungekho umugqa wokuhlola.
Njengoba kuboniswe emkhiwaneni.7, ukujula komgodi okukhulu okudalwe i-Pseudomonas aeruginosa biofilm kwaba ngu-0.69 µm, okukhulu kakhulu kune-abiotic medium (0.02 µm).Lokhu kuvumelana nedatha ye-electrochemical engenhla.Ngaphansi kwezimo ezifanayo, ukujula komgodi okungu-0.69 µm kuncane ngokuphindwe kashumi kunevelu engu-9.5 µm ecaciswe ku-2205 DSS40.Le datha ibonisa ukuthi i-2707 HDSS ibonisa ukumelana okungcono kuma-MIC kune-2205 DSS.Lokhu akumangazi njengoba i-2707 HDSS inezinga eliphezulu le-Cr, elivumela ukudlula isikhathi eside, kwenza i-Pseudomonas aeruginosa ibe nzima kakhulu ukuyikhipha, futhi iqala inqubo ngaphandle kwemvula yesibili eyingozi i-Pitting41.
Sengiphetha, i-MIC pitting itholwe ezindaweni ezingu-2707 HDSS kumhluzi we-Pseudomonas aeruginosa, kuyilapho i-pitting yayingekho kumidiya ye-abiotic.Lo msebenzi ubonisa ukuthi i-2707 HDSS inokumelana okungcono ne-MIC kune-2205 DSS, kodwa ayivikelekile ngokuphelele ku-MIC ngenxa ye-Pseudomonas aeruginosa biofilm.Le miphumela isiza ekukhetheni izinsimbi ezingenasici ezifanele kanye neminyaka yokuphila kwemvelo yasolwandle.
Amasampula e-HDSS angu-2707 ahlinzekwe yiSikole Sezensimbi, i-Northeastern University (NEU), i-Shenyang, e-China.Ukwakheka okuyisisekelo kwe-2707 HDSS kuboniswa kuThebula 1, elahlaziywa Ukuhlaziywa Kwezinto kanye Nomnyango Wokuhlola weYunivesithi yaseNyakatho-mpumalanga.Wonke amasampuli aphathwe ngesisombululo esiqinile ku-1180 ° C ihora elingu-1.Ngaphambi kokuhlolwa kokugqwala, insimbi ye-HDSS engu-2707 enendawo eveziwe engu-1 cm2 yayipholishwe yaba igridi engu-2000 nge-silicon carbide sandpaper yase ipholishwa futhi nge-0.05 µm Al2O3 powder slurry.Izinhlangothi nangaphansi kuvikelwe ngopende ongenayo.Ngemuva kokoma, amasampula ahlanzwa ngamanzi angcolile ahlanjululwe futhi afakwe inzalo nge-ethanol engu-75% (v/v) amahora angu-0.5.Bese zomiswa emoyeni ngaphansi kokukhanya kwe-ultraviolet (UV) amahora angu-0.5 ngaphambi kokusetshenziswa.
I-Marine strain Pseudomonas aeruginosa MCCC 1A00099 yathengwa kwa-Xiamen Marine Culture Collection (MCCC), e-China.I-Marine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China) yayisetshenziselwa ukukhiqiza i-Pseudomonas aeruginosa kumaflaski angu-250 ml kanye namaseli engilazi kagesi angu-500 ml ngaphansi kwezimo ze-aerobic ku-37°C.Okumaphakathi kuqukethe (g/l): 19.45 NaCl, 5.98 MgCl2, 3.24 Na2SO4, 1.8 CaCl2, 0.55 KCl, 0.16 Na2CO3, 0.08 KBr, 0.034 SrCl2, 0.08 20 2 Na2SO, 2 Na20, 2 Na2CO3. 0.008, 0.008 Na4F0H20PO.I-1.0 yeast extract kanye ne-0.1 iron citrate.I-Autoclave ku-121 ° C imizuzu engu-20 ngaphambi kokujova.Amaseli e-Sessile nama-planktonic abalwa ngaphansi kwesibonakhulu esikhanyayo kusetshenziswa i-hemocytometer ekukhuliseni okungu-400x.Ukuhlushwa kokuqala kwamaseli e-planktonic P. aeruginosa ngokushesha ngemva kokujova cishe kwakungamaseli angu-106/mL.
Ukuhlolwa kwe-electrochemical kwenziwa esitokisini seglasi le-electrode yakudala enevolumu ephakathi kwama-500 ml.Ishidi leplatinamu kanye ne-saturated calomel electrode (SCE) kuxhunywe ku-reactor nge-Luggin capillary egcwele ibhuloho likasawoti futhi yasebenza njengama-electrodes ekhawunta nereferensi, ngokulandelanayo.Ukuze udale i-electrode esebenzayo, ucingo lwethusi olunamekwe ngenjoloba lwalunamathiselwe kusampula ngayinye futhi lumbozwe nge-epoxy, lushiya cishe u-1 cm2 wendawo engaphezulu ohlangothini olulodwa lwe-electrode esebenzayo.Ngesikhathi sokukalwa kwe-electrochemical, amasampula abekwe endaweni engu-2216E futhi agcinwe ezingeni lokushisa elingaguquki le-incubation (37°C) endaweni yokugeza yamanzi.I-OCP, LPR, EIS kanye nedatha ye-dynamic polarization kwalinganiswa kusetshenziswa i-Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA).Ukuhlolwa kwe-LPR kwarekhodwa ngesilinganiso sokuskena esingu-0.125 mV s-1 ebangeni le--5 ne-5 mV kanye ne-Eocp enesilinganiso sesampula esingu-1 Hz.I-EIS yenziwa endaweni enganyakazi ye-Eocp kusetshenziswa i-voltage esetshenziswayo engu-5 mV ene-sinusoid ebangeni lemvamisa lika-0.01 kuya ku-10,000 Hz.Ngaphambi kokushanela okungenzeka, ama-electrode abekwimodi yesekethe evulekile kuze kube yilapho kufinyelelwa khona amandla okugqwala amahhala angama-42.Nge.Ukuhlolwa ngakunye kwaphindwa kathathu nge-Pseudomonas aeruginosa nangaphandle kwayo.
Amasampuli okuhlaziya i-metallographic apholishwa ngomshini ngephepha le-SiC elimanzi legrit engu-2000 abese epholishwa nge-0.05 µm Al2O3 powder slurry ukuze abonwe ngamehlo.Ukuhlaziywa kwe-metallographic kwenziwa kusetshenziswa isibonakhulu esibonakalayo.Isampula yaqoshwa nge-10 wt% isisombululo se-potassium hydroxide43.
Ngemva kokufukamela, geza izikhathi ezi-3 nge-phosphate buffered saline (PBS) (pH 7.4 ± 0.2) bese ulungisa nge-2.5% (v/v) glutaraldehyde amahora angu-10 ukulungisa i-biofilm.Ukuphelelwa amanzi kwamanzi okwalandela nge-ethanol ochungechungeni olunyathelwe (50%, 60%, 70%, 80%, 90%, 95% no-100% ngevolumu) ngaphambi kokoma komoya.Ekugcineni, ifilimu yegolide yafafazwa phezu kwesampula ukuze kuhlinzekwe ukuqhutshwa kokubhekwa kwe-SEM44.Izithombe ze-SEM zigxile endaweni enamaseli e-P. aeruginosa asungulwe kakhulu endaweni yesampula ngayinye.Ukuhlaziywa kwe-EMF kwenziwa ukuze kutholwe izakhi zamakhemikhali.Ukuze kukalwe ukujula komgodi, kwasetshenziswa isibonakhulu se-Zeiss confocal laser scanning (CLSM) (LSM 710, Zeiss, Germany).Ukuze ubuke imigodi yokugqwala ngaphansi kwe-biofilm, isampula yokuhlola yaqale yahlanzwa ngokuvumelana ne-Chinese National Standard (CNS) GB/T4334.4-2000 ukuze kukhishwe imikhiqizo yokugqwala kanye ne-biofilm ebusweni besampula yokuhlola.
I-X-ray photoelectron spectroscopy (XPS, ESCALAB250 Surface Analysis System, Thermo VG, USA) ukuhlaziywa kusetshenziswa umthombo we-X-ray we-monochromatic (umugqa we-Al Kα onamandla angu-1500 eV namandla angu-150 W) kumandla abanzi ahlanganisayo. 0 ngaphansi kwezimo ezijwayelekile -1350 eV.Rekhoda isibukeli sokucaca okuphezulu usebenzisa amandla okudlula angu-50 eV kanye nosayizi wesinyathelo esingu-0.2 eV.
Susa isampula efukanyelwe bese uyigeza kahle nge-PBS (pH 7.4 ± 0.2) ku-15 s45.Ukubona ukusebenza kwebhaktheriya kwe-biofilm kusampula, i-biofilm yangcoliswa kusetshenziswa Ikhithi Yokusebenza Kwebhaktheriya OKUPHILA/DEAD (I-Invitrogen, Eugene, NOMA, USA).Ikhithi iqukethe odayi ababili be-fluorescent: udayi we-fluorescent oluhlaza we-SYTO-9 kanye nodayi we-propidium iodide (PI) obomvu we-fluorescent.Ku-CLSM, amachashazi aluhlaza nabomvu ane-fluorescent amelela amaseli aphilayo nafile, ngokulandelana.Ukuze ugcobe, fukamela u-1 ml wengxube equkethe u-3 µl we-SYTO-9 no-3 µl wesisombululo se-PI ekamelweni lokushisa (23°C) ebumnyameni imizuzu engu-20.Ngemva kwalokho, amasampula anamabala aqashelwa kumaza amaza amabili (488 nm kumaseli aphilayo kanye no-559 nm wamaseli afile) kusetshenziswa i-Nikon CLSM apparatus (C2 Plus, Nikon, Japan).Linganisa ukujiya kwe-biofilm ngemodi yokuskena engu-3-D.
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